1. Field of the Invention
The present invention relates to a drawing processing apparatus, and more particularly to a drawing processing apparatus which performs drawing processing by inputting drawing instructions.
2. Description of the Prior Art
Presently, page printers execute printing by inputting PDL (page description language) such as Interpress (a trademark of U.S. Xerox Corporation) and PostScript (a trademark of U.S. Adobe Systems Incorporated).
Printing by input of such PDLs requires imaging processing which converts data of a PDL format into data of a format suitable for a raster output device. However, the imaging processing generally requires a very long time, posing a problem to a system which makes output to a high-speed page printer.
For example, although some color high-speed page printers have an output capacity of 40 sheets or more per minute, image processing requires from tens of seconds to several minutes, making it difficult to deliver the full capacity of expensive page printers. Accordingly, to perform imaging processing rapidly, parallel drawing processing is required.
FIG. 1 shows a drawing area split equally for parallel drawing. A drawing element 4 in this figure is complicatedly overlapped with a number of elements at the center of the drawing area. For such a drawing element 4, with the area being equally split into a plurality of subareas, parallel processing is performed in the drawing processing sections 1 to 3.
However, as described above, even if the area of the drawing element 4 is equally split and the resulting subareas are equally assigned to the drawing processing sections 1 to 3, because of the complexity of drawing elements themselves such as the number of drawing elements and the overlapping of different graphics, different loads are put on the drawing processing sections 1 to 3.
FIG. 2 shows the respective drawing processing operation timings of the drawing processing sections shown in FIG. 1. A processing time per unit drawing area shown by the timings includes influences caused by the degree of overlapping among different drawing elements in addition to the number of drawing elements belonging to each area. The figure shows that a load concentrates on the drawing processing section 3 in charge of more complex drawing elements than in the drawing processing sections 1 and 2, so that other drawing processing sections 1 and 2 are driven into a wait state.
Performing parallel drawing processing with a drawing area being equally split as described above poses a problem in that processing of a drawing processing section assigned a heavy load slows down and the effect of parallel drawing processing is reduced.